(1) Field of the Invention
The present invention relates to a coated sheet material and a process for producing same. More particularly, the present invention relates to a coated sheet material which can be used for a paraglider and a spinnaker, and a process for producing same.
(2) Description of the Related Art
Recently, paragliding has become tremendously popular, because anyone is able to fly thereby. For example, after climbing to the top of a high mountain it is easy and thrilling to come down again by paragliding.
A paraglider has the following indispensable features.
First, the paraglider must be safe, and therefore, must gave a guaranteed high and durable mechanical strength, for example, seam strength and tear strength of the sheet material from which the paraglider is made, for normal use thereof.
Second: the paraglider must be light weight, as a light weight effectively enhances the flying property of the paraglider and makes it easily portable.
Third, the paraglider must be waterproof. Namely, it must hot absorb rain water, which would increase the weight thereof.
Additionally, the paraglider must be made from a sheet material having a satisfactory surface smoothness, color fastness, and dimensional stability.
The paraglider has been developed from a conventional parachute, which is usually made of a nylon fiber fabric as described in, for example, Japanese Unexamined Patent Publication No. 54-49799. Also, the nylon fiber fabric for forming the conventional parachute is coated with a known coating polymer material. This coating polymer material usually comprises a polyurethane resin and has a high weather resistance.
Conventional paragliders do not always satisfy all of the above-mentioned indispensable features, especially a high mechanical durability and a light weight. Namely, some conventional paragliders have an unsatisfactory heavy weight when carried, and thus are not easy to haul over a long distance or when climbing to a high position.
Also, to obtain a paraglider having a high mechanical strength and durability, the paraglider is necessarily made from a woven fabric which comprises a number of thick yarns or which has high weaving density.
The use of the thick yarns and the high weaving density makes the paraglider very heavy.
Further, the conventional nylon fiber fabrics for a paraglider are wetted by rain or mist, thus resulting in an increase in the weight of the paraglider and a formation of wrinkles on the surface of the paraglider, thereby adversely affecting the surface smoothness of the paraglider, and thus harming the flying properties and stability of the paraglider.